As camcorders and other video recording devices (i.e., digital still cameras, mobile phones, etc.) continue to shrink in size, and as zoom ratios continue to increase, it becomes increasingly difficult for users to steadily hold a camera to produce stable video.
Camera ergonomics may not allow holding the device in a stable and comfortable position and thus promote unstable holding of the device. Also, because of the highly mobile nature of these devices, people are increasingly capturing video in less than ideal situations (i.e., outdoor activities, sporting events, etc.) as opposed to contrived in-door events. Therefore, there is less opportunity for properly supporting the camera during recording.
Furthermore, as optics continue to improve, magnification capabilities are often incorporated in such devices. High magnification factors (i.e., zooming) contribute to the unstable appearance of video since such zooming amplifies every small movement of the hand of the user.
Camera jitter (i.e., mechanical instability) introduces extraneous motion during video capture. The extraneous motion is not related to the actual motion of objects in the picture. Therefore, the motion appears as random picture movements that produce disturbing visual effects. The motion can be difficult to encode at low bit rates. The end result is video material that is hardly usable from both practical and aesthetic perspectives.
Camcorder manufacturers have implemented various ways of implementing image stabilization. One way is to use mechanical correction, including piezo-electric physical displacement, optical system fluid coupling/dampening and other mechanical dampening devices. Another way of solving the problem is by electronic correction (i.e., digital signal processing) using external sensors.
Current digital image stabilization solutions are limited by the type of processors used in typical cameras. These processors are more geared toward Image/Sensor Processing and therefore do not have easy access to the sophisticated motion estimation statistics commonly available in hybrid entropy video encoder/decoders (Codecs). Furthermore, in cases when a digital stabilization is used in the context of a video Codec, a large number of motion vectors are used in a single pass without a flexible selection of areas of motion and in a non-hierarchical motion estimation architecture.
It would be desirable to remove extraneous motion from an input video signal to produce a stabilized sequence of pictures that is more visually pleasing and/or more easily compressed.